Apparatus for forming sand molds



Feb. 2, 1937. G|LL 2,069,669

APPARATUS FOR FORMING SAND MOLDS Filed Aug. 12, 1935 3 Sheets-Sheet l INVENTOR. Fran/r F? c;

j BY g ATTORNEY.

Feb. 2, 1937. F. P. GILL APPARATUS FOR FORMING SAND MOLDS 3 Sheets-Sheet 2 Filed Aug. 12,

IRE-Z INVENTOR. FFqn/f I 617/.

ATTORNEY.

Feb. 2, 1937. F. P. GILL APPARATUS FOR FOIAMING SAND MQLDS Filed Aug 12, 1935 3 Sheets-Sheet 3 INVENT OR. flan/r P 6/7/ ATTORNEY.

Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE Claims.

ing ridges or fins are an important feature of cast metal brake drums and have heretofore been provided thereon by machining grooves in an annular surface of the drum to leave such ridges or fins upstanding. The machining of the cast metal brake drums to provide the desired ridges or fins has involved considerable additional expense in the way of excess metal contained in the castings and in the way of labor and machine operations. By my novel method and apparatus, as will be hereinafter more fully explained, the sand mold is provided with one or more undercut recesses or grooves whereby the desired projections or ridges are cast integral on the brake drum or other article being produced.

It is therefore an object of the present invention to provide a novel method of molding wherein the cavity of a green sand mold is extended by removing sand from the wall of the cavity and thereby forming an undercut recess or groove therein.

Another object of the invention is to provide a novel method of molding involving the forming of a green sand mold with a cavity therein having substantially the shape of the body of the casting desired and removing sand from the wall of the cavity and thereby forming undercut recesses or grooves therein corresponding with projections or fins desired on the casting, and smoothing the sand in and adjacent the recesses or grooves being formed.

Still another object of this invention is to provide a novel method of molding wherein the forming of the undercut grooves or recesses is accomplished by the action of a cutter which removes sand from the wall of the mold cavity, and the smoothing of the sand in the grooves or recesses is accomplished by rolling.

A further object of the invention is to provide a novel method of molding comprising the forming of undercut grooves or recesses in the wall of a mold cavity and meanwhile supporting the sand of the wall adjacent the point at which the undercut grooves or recesses are being formed.

It is also an object of this invention to provide novel apparatus for forming undercut grooves or recesses in the wall of a sand mold, ,5 comprising a cutter for removing sand from the cavity wall and means operable in associated relation with the cutter for smoothing the sand in the recesses or grooves formed by the cutter.

Still another object of the invention is to pro- 10 vide novel molding apparatus'having means for removing sand from the wall of a mold cavity to thereby form an undercut groove therein, and also having means for supporting the sand of the wall during the forming of the groove.

Yet another object of the invention is to provide novel molding apparatus embodying a rotatable head adapted to extend into the cavity of a sand mold, and cutting and smoothing means carried by the head for cooperation with the wall 20 of the mold cavity during rotation of the head therein.

Other objects and advantages of the invention will be apparent from the following description when taken in conjunction with the accompanying sheets of drawings wherein Fig. 1 is a partial side elevational View showing molding apparatus, constructed according to my invention and which may be used in practicing my novel method.

Fig. 2 is a plan view thereof.

Fig. 3 is a partial transverse sectional view of the apparatus taken on line 33 of Fig. 2 and showing a sand mold in position on the appa- Fig. 4 is a plan view of the rotatable head.

Fig. 5 is a side elevation thereof.

Fig. 6 is a partial sectional view taken through the rotatable head as indicated by the line 6-6 of Fig. 4. 40

Fig. 7 is another partial transverse sectional View of the head taken as indicated by line '|--'l of Fig. 4.

Fig. 8 is a partial sectional View, on a larger scale, showing the shape of the ridges of the smoothing roll, and

Fig. 9 is a partial plan view of the head showing another manner of mounting the cutting and smoothing means thereon.

{More detailed reference will now be made to the accompanying drawings for the purpose of describing my novel method and apparatus for making sand molds. It will be understood, of course, that the apparatus shown in the draw- 7 ings is to be regarded as illustrative only and 55 that the apparatus and method of the invention may be varied within the scope of the appended claims.

My novel molding apparatus comprises in general a table-like support or frame I0. having thereon a rotatable head II which is adapted to extend into the recess of a sand mold I2 when the latter is supported on the frame, as shown in broken lines in Fig. 1 of the drawings. The rotatable head, aswill be explained more in detail hereinafter, is provided with an arcuate projection or segment I3 for supporting engagement with the wall of the mold cavity, and with cutting and smoothing means I4 and I5 which cooperate with the cavity wall to form undercut grooves or recesses therein corresponding with the projections or fins desired on the castings to be produced.

The frame II] may be constructed as shown in Figs. 1 and 2 of the drawings with a box-like section I8 having supporting legs I9 at the corners thereof, and may be provided with a platelike top 20 which is adjustably supported on the 4 section I8.

;suitable means such as a spider-like upon which the rotatable head The frame section I8 maybe provided substantially centrally thereof with a vertically extending bearing sleeve 2| having ashaft 22 mounted therein for operating the rotatable head II. The bearing sleeve 2| may be supported from the sides of the frame section I8 by arrangement of the ribs 23.

One end of the shaft 22 extends upwardly above the plane of the top 20 through an opening 25 of the latter in the form of a spindle 26 H is mounted. The lower end of the shaft 22-extends below the bearingsleeve 2| and may be connected to any suitable motor or driving device such as the electric motor 21. The motor 21 may be mounted on the frame It in any convenient manner and may be drivingly connected to the shaft 22 by suitable means such as the beveled gears 28.

The rotatable head II is preferably construct ed as a cast metal drum of such size and shape that it will readily enter or project into the cavity 38 of the sand mold I2 when a mold box or section 3| containing such a sand mold is placed on the top 20, as shown in Figs. 1 and 3. The arcuate supporting projection I3, of the rotatable head may extend over a desired portion of the periphery of the drum and may be formed as an integral part of the drum structure. The drum forming the rotatable head II is preferably of hollow construction for the sake of lightness and also to accommodate therein the cutting and smoothing means or devices I4 and I5. The rotatable head may be provided centrally thereof with a hub orboss 33 which may be keyed or otherwise drivingly connected to the spindle 26 of the driving shaft 22.

At a point diametrically'opposite the supporting projection I3 the drum may be provided'with an increased body of metal to constitute a counterweight 34 for counterbalancing the projec- .tion and the devices I4 and I5.

extending ridges'and grooves 38 and 39 which are spaced apart to correspond with the spacing of the fins and, grooves of the brake drum or other cast metal articles to be produced; When.

corresponding relatively low ridges on the cavity wall.

At one point of the arcuate surface of the projection I3, I provide a plurality of slots 40 in line with the ridges 38, and which extend through the wall of the rotatable head and communicate with the hollow interior thereof. At another point of the projection I3, I provide similar slots 4| in line with the ridges 38, and which also extend through the wall of the head and communicate withthe hollow interior theresmoothing device I5 which will be presently explained, is mounted on the head with portions thereof arranged to extend outwardly through the slots 4| for smoothing cooperation with the sand of the cavity wall.

The cutting device I4 may comprise an arm 43 which is pivoted to swing on a pivot pin 44 of the head, and a cutter 45 which is carried by the arm 43 and has finger-like cutting elements 46 adapted to be projected outwardly through the slots 40. The cutting elements are normally held in retracted position inwardly of the face of the supporting projection I3 by means, of the tension spring 48 but are adapted to be projected outwardly through the slots when the arm 43 is swung outwardly against the action ofthe spring by centrifugal force.

' The extent to which the cutting elements 46 may be projected through the slots 40 may be limited by a stop 49 provided on the arm 43 to cooperate with an'abutment 501 of the rotatable head. The stop 49 may have an adjustable contact, such as the screw 5| threaded therein, for engagement with the abutment 50. i

The cutting elements 46 may be provided with relatively sharp leading edges or corners 52 which cut through the sand to form the grooves as the head is rotated. These elements may also be provided with inclined faces 53 extending inwardly and rearwardly from the leading edges 52 at such an angle that the sand removed from the wall of the cavity by the cutting elements will be deflected or thrown inwardly through the slots 40 and into the hollow interior of the rotatable head from which the sand may fall freely downwardly through the opening 25 of the top 20.

The grooves cut in the wall of the mold cavity by the elements 46 are of substantially a cross sectional shape and size to correspond with the cross sectional shape and size of the fins and projections desired on the brake drums or other cast articles to be produced. The sand of the cavity wall adjacent the undercut grooves thus formed is supported and smoothed by the projection or segment I3 of the rotatable head II and the sand in the grooves is smoothed by the device I5. This device comprises a roller 55 hav- 7 5,

ing spaced ridges or flanges 55 which may be projected outwardly through the slots 4| to engage in the grooves formed by the cutting elements 46. The roller 55 is rotatably mounted on a swinging arm 51 which is in turn mounted on a pivot pin 58 of the rotatable head. The arm 5'! may also be provided with a-stop projection 59 for limiting the extent to which the ridges 56 may be pro jected through the slots 4|. The projection 59 may carry an adjustable contact screw 60 for engagement with the abutment 50.

To facilitate the removal of the sand cuttings and to prevent sand from sticking or adhering to the inner faces of the intervening bar-like portions 62 and 63 of the projection |3, I construct these bar portions with a cut-away or inclined inner face 5 as shown in Fig. '7. These inclined faces of the bar portions 62 and 53 allow the loose sand to readily fall downwardly on the inside of the rotatable head.

The ridges or flanges 55 of the smoothing roll 55 have their rims tapered to correspond in shape with the fin shape desired on the cast article to be produced, and as these rims operate in the grooves they smooth the sand to the shape which the fins of the cast article are to have. The portions of the ridges which extend through the slots 4 as indicated in Fig. 8, merge smoothly with the edges of the grooves 38 on the outer face of the projection I3, this being obtained by providing the fillet portions 56 on the projection.

The roller 55 is normally held in a retracted position by a tension spring 55 but is moved outwardly by centrifugal force to project the ridges 56 through the slots 4 l When the rotatable head is disposed in operating position Within the cavity of a sand mold, such as the mold l2, the ridges 38 of the projection l3 are pressed into the sand of the cavity wall, as mentioned above, and hence provision must be made for bringing the cavity wall and the projection into such cooperating relation without injury to the sand mold. While this may be accomplished in various ways, I have in this instance shown means for causing relative lateral movement between the mold and the rotatable head H to bring the projection l3 thereof into enagement with the wall of the cavity. This means comprises an adjustable mounting for the top 2'6 whereby this top, with the mold l2 supported thereon, may be moved laterally with respect to the rotatable head I For this purpose I may provide the underside of the top 2|] with spaced parallel grooves 6'6 into which guide projections or flanges 61 of the frame section |8 extend. At opposite ends of the top 29, I may provide depending lugs 63 which have adjusting screws 59 extending therethrough. The screws 69 engage the sides of the frame section l8 and move the top 20 laterally with respect to the frame section as the screws are operated. During such shifting of the top, its movement is guided by the projections 61 engaging in the parallel groove 66.

The top 2|! may be provided with means for 10- cating the mold section 3| thereon, such as the projecting pins 10 which engage in the usual ears 1| of the mold section when the latter is placed on the top. The top may also be provided with an annular member 12 extending around the opening 25 and of such cross sectional shape as to cooperate with this portion of the sand mold.

In the use of my molding apparatus and in carrying out my novel mold forming method, the mold I2 is first formed in the mold section 3| and the mold section is then placed on the top 28 for the grooving operation. In forming. the mold l2 the sandis packed around a pattern: which has a shape corresponding substantially with the shape of the body portion of the brake drum or other article to be produced. The withdrawal of the pattern. fromthe sand leaves a smooth sided substantially cylindrical mold cavity 30 ther.ein. When the mold is placed on the top 20 in the position shown in Figs. 1 and 3 the rotatable head extends into the cavity 30 while the portions. of the mold around the edge of the cavity engage the annular member 12. By rotating the screws 69 the top 28, with the mold thereon, is shifted laterally with respect to the rotatable head H and the projection i3 is thereby brought into engagement with the wall of the cavity and the ridges 38 of the projection are pressed into the same.

The apparatus is now in readiness for the motor 21 to be started, and when started it operates to rotate the head at relatively high speed. Initial rotation of thehead causes the ridges and grooves 38 and 39 of theprojection l3 to form corresponding grooves and ridges on the inner surface of the wall of the mold cavity. As the speed of rotation of the head increases centrifugal force acts on the cutting device l4 and causes the cutting elements-46 to be projected outwardly through the slots 40. Rotation of the head with the cutting elements thus projected causes the elements to cut grooves in the side wall of the mold cavity.

As the speed of rotation of the head increases further, the smoothing device I5 is swung out by centrifugal force to cause the ridges 56 of the roller 55 to be projected through the slots 4| and into smoothing cooperation with the grooves which have been formed by the cutting elements 46. During the cutting and smoothing of the grooves by the respective devices l4 and I5, the projection l3 remains in contact with the wall of the mold cavity and supports the sand thereof against loosening and crumbling.

After such rotation of the head I! the driving motor 21 is stopped and the screws 69 are operated to move the top 20 in a direction to separate the projection I3 from the wall of the mold cavity, whereupon the mold may be lifted from the top 20 without injury to the undercut grooves which have now been formed in the cavity wall.

It is not necessary to my invention that the cutting and smoothing devices be separately mounted on the rotatable head, but may be carried by the same supporting member or arm. For example, cutting and smoothing devices l4 and |5', which are of similar construction to corresponding devices M and I5, may be both mounted on a single pivoted arm 14 to be projected from the rotatable head H for cooperation with the wall of a mold cavity.

From the foregoing description and the accompanying drawings it will now be readily understood that I have provided a novel apparatus and method for forming grooved sand molds for the production of cast metal articles having projections thereon such as cast metal brake drums having annularly extending ridges or fins thereon. It will be understood further that by my novel method and apparatus sand is removed from the wall of the mold cavity to form the undercut grooves or recesses and the sand in and adjacent the grooves is supported and smoothed so that after the grooving operation the mold will have a. desired smooth and accurate shape.

While I have illustrated and described. my

molding apparatus and method in a somewhat detailed manner, it will be understood of course, that I do not wish to be limited to the precise details of construction and steps of procedure herein described, but regard my invention as including such changes and modifications asdo not constitute a departure from the spirit of the invention and the scope of theappended claims.

I claim:

1. In molding apparatus the combination of a rotatable head adapted to extend into the cavity of a sand mold and having a ridged segment in contact with the wall of the cavity during rotation, means for rotating said head, said segment having-slots therein in line with the ridges thereof, and cutting elements adapted to be projected through said slots for forming grooves in the cavity wall.

' 2. In molding apparatus the combination of a rotatable head adapted to extend into the cavity of a sand mold and having a ridged segment in contact with the wall of the cavity during rotation, means for rotating said head, said segment having slots therein in line with the ridges thereof, cutting elements adapted to be projected through said slots for forming grooves in the cavity wall, and a roller having ridged portions adapted to be projected through said slots for smoothing the grooves.

3. In molding apparatus the combination of a rotatable head adapted to extend into the cavity of a sand mold and having a ridged segment in contact with the wall of the cavity during rotation, means for rotating said head, said segment having slots therein in line with the ridges thereof, and shifta-ble members on said head centrifugally operable in succession, one having teeth tact with the sand wall of the cavity during rotation of the head, said segment being slotted, cutters movably mounted on the head and movable through someof the slots in the segment to cut grooves in the said wall during said rotation, and smoothing devices carried by the head'and movable outwardly into said grooves through other slots in the segment.

5. The combination stated in claim 4, the smoothing devices comprising a roller having ridges which project through said other slots and into grooves as the head is rotated.

FRANK P. GILL. 

